Nanoparticles as Antibiotic-Delivery Vehicles (ADVs) Overcome Resistance by MRSA and Other MDR Bacterial Pathogens: The Grenade Hypothesis

Amjed Alabresm, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC, United States; Center for Environmental Nanoscience and Risk (CENR), University of South Carolina, Columbia, SC, United States; Department of Biological Development of Shatt Al-Arab & N. Arabian Gulf, Marine Science Centre, University of Basrah, Basrah, Iraq.
Yung Pin Chen, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC, United States.
Savannah Wichter-Chandler, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC, United States.
Jamie Lead, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC, United States; Center for Environmental Nanoscience and Risk (CENR), University of South Carolina, Columbia, SC, United States.
Brian C. Benicewicz, Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, United States.
Alan W. Decho, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC, United States. Electronic address: awdecho@mailbox.sc.edu.

Abstract

OBJECTIVES: The aim of this study was to examine how the concentrated delivery of less effective antibiotics, such as the β-lactam penicillin G, by linkage to nanoparticles (NPs), could influence the killing efficiency against various pathogenic bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and other multidrug resistant (MDR) strains. METHODS: The β-lactam antibiotic penicillin G (PenG) was passively sorbed to fluorescent polystyrene NPs (20nm) that were surface-functionalized with carboxylic acid (COO-NPs) or sulfate groups (SO-NPs) to form a PenG-NP complex. Antimicrobial activities of PenG-NPs were evaluated against Gram-negative and Gram-positive bacteria, including antibiotic resistant strains. Disc diffusion, microdilution assays and live/dead staining were performed for antibacterial assessments. RESULTS: The results showed that bactericidal activities of PenG-NP complexes were statistically significantly (P<0.05) enhanced against Gram-negative and Gram-positive strains, including MRSA and MDR strains. Fluorescence imaging verified that NPs comigrated with antibiotics throughout clear zones of MIC agar plate assays. The increased bactericidal abilities of NP-linked antibiotics are hypothesized to result from the greatly increased densities of antibiotic delivered by each NP to a given bacterial cell (compared with solution concentrations of antibiotic), which overwhelms the bacterial resistance mechanism(s). CONCLUSIONS: As a whole, PenG-NP complexation demonstrated a remarkable activity against different pathogenic bacteria, including MRSA and MDR strains. We term this the 'grenade hypothesis'. Further testing and development of this approach will provide validation of its potential usefulness for controlling antibiotic-resistant bacterial infections.